At present, most fluid dispensing applicators are only capable of spraying along a direction longitudinal to the applicator, i.e., in a straight forward direction. However, in practice, an operator is often confronted with the task of coating the backside or "unviewable side" of a structure. The unviewable side is typically inaccessible because it is covered by a panel or other obstacle. In aerospace, this situation arises frequently; for example, the unviewable side of "stringers" in an airplane wing must be coated with a liquid/fluid. This work is presently performed manually using bent brushes. The disadvantage to this form of application is that it is expensive, unreliable, and uncomfortable to perform.
A further disadvantage to the use of bent brushes to apply coatings to an unviewable surface is that some coatings cannot be applied onto a surface in the desired quantity or quality using this form of application. Further, obtaining an even coating using a bent brush is virtually impossible.